Bile salt hydrolase activity of enterococci isolated from food: Screening and quantitative determination

One hundred seventeen enterococcal strains isolated from food (47 Enterococ cus faecium, 48 Enterococcus faecalis, 16 Enterococcus durans, 2 Enterococc us gallinarum, 3 Enterococcus casseliflavus, and 1 Enterococcus malodoratus ) were screened for bile salt hydrolase (BSH) activity on de Man, Rogosa, a nd Sharpe agar medium containing taurocholic acid and calcium chloride. The highest incidence of BSH-active strains was observed for E. faecalis (81%) followed by E. faecium (50%) and E, durans (44%). Isolates were grouped in to four putative activity groups (no, low, medium, and high activity) based on the size of precipitation zones observed in the screening experiment. O ur results showed that assumptions on BSH activity based on the size of bil e precipitation zones in screening experiments did not correlate with actua l activity as quantified by high-pressure liquid chromatography, but the sc reening assay is useful for assessing the presence or absence of BSH activi ty.